Conventionally, it is known that a data file, etc. is hierarchically displayed in a tree form. For example, an information processing device (personal computer or the like) stores a file system for managing by classifying a data file using a root directory and its lower layer sub-directory. In this device, when a symbol (icon) indicating a root directory that is displayed on a monitor is selected using a pointing device, a symbol indicating a sub-directory is displayed such that it branches from the symbol indicating the root directory. Further, when the symbol indicating the sub-directory is selected using the pointing device, names or the like of a data file that is stored in the sub-directory are displayed on the monitor.
Furthermore, in recent years, multiple information processing devices are interconnected via a network; here, data files of the devices are often shared by the multiple devices. In each of these information processing devices, symbols of the data files stored in other devices are hierarchically displayed along with those stored in the own (e.g., see JP-H10-021042 A (U.S. Pat. No. 5,991,798)).
Meanwhile, vehicles (in particular, automobiles) are increasing in recent years, the vehicles that have: in-vehicle information devices communicating with the Internet, such as an audio device and a navigation device; or devices for achieving safety and comfort within the vehicles such as an anti-theft device and an emergency call device. Information and functions within the vehicles are thereby diversified.
Derived from the above background, the vehicles become to include various mixed information such as: vehicular information having a high privacy level; necessary information for maintaining the vehicle; and entertainment information of image data, music data, etc. Under the state of the various mixed information co-existing, when information included in the vehicle is displayed, several problems arise. Namely, much information unnecessary for a user is displayed; further, information unsuitable for a specific user is displayed for the specific user.
Furthermore, also in recent years, music data or the like is transferred from a personal computer located at home to a hard disk drive of an audio device mounted in a vehicle using a portable storage medium such as a memory card. However, it is unfavorable for a user to transfer data using the memory card having the much less data volume than the hard disk drive, so that improvement is being expected.